In the manufacture of components, it is often desirable to create a seal between a first component and a second component at a precise location. In order to produce a fluid-tight interference fit between the first and second components, an undercut defining a groove is generally required to be cut from either the first or second component so as to receive the seal therein. The tolerances placed on the groove determines the effectiveness of the seal and is subject to large variations due to the types of materials used. It has been found that plastic encapsulation of a seal member insert substantially reduces the cost of final assembly.
For encapsulating in plastic by an injection insert-molding process, an upper mold plate and a lower mold plate forming a cavity therebetween is used. The seal member insert is placed in the mold and then the two plates of the mold are closed. A molten plastic is then forced into the cavity in a well-known manner and hardened about a portion of the seal to form a finished plastic package. Thereafter, the two plates of the mold are opened and the finished package is ejected.
The problem encountered in the prior art is that during the injection stage of the process the high injection pressure will cause the seal insert, being of a compressible material, to move or shift around in the mold. As a result, the precise location of the seal within the finished outer housing could not be controlled. Further, due to the difficulty in maintaining tight tolerances on the undercuts formed on the outer housing for receiving the seal, an effective seal was not always achieved.
It would therefore be desirable to provide an improved method of encapsulating a seal member within a mold so that it will be located precisely relative to the molded outer housing. It would also be expedient that the method of molding provides an effective and efficient seal each time without requiring tight tolerances on the undercuts formed in the outer housing.